Ming's boat has lots of weather helm. It exists with both rudders (that is, if I lift one or the other the weather helm is still there.) I guess in a physics sense since it's a unirig I shouldn't be super surprised, but is there any way to reduce the weather helm besides adjusting the rudder rake a bit?

Mast rake or rudder rake... that is the choice, so rudder rake is the prefered answer. They need to rake forward more, but be sure they are actually locking first. If they don't lock properly or tightly, they may be slipping aft as she sails.

They're locking down okay, so I guess rake it is. I'll use the standard rudder-hole-drilling template for the holes, but can you tell me if you think that'll be sufficient, or is the template for less rake than I might want? I mean no kidding, you probably have to keep 10-12 lbs. of pressure on the hiking stick at all times; it's crazy. And tiring!

Personally I would do the obvious and easy thing first- mast rake. Get your sidestays to the bottom hole or close, forstay in the top. Use your mainsheet system plus a trapeze for leverage at each side. See what, if any, difference it makes.
THEN go after the rudder. From what I have seen, changing the rudder around will provide no real challenge to you. I am sure that you already checked this out, but here is good stuff for other perusers
http://static.hobiecat.com/2010_archive/support/pdfs/32_33.pdf

_________________The fact that this windy world is largely covered in water obviously means that man was meant to sail.

For proper rake adjustment you may need to try several settings. Helm feel will change with different mast rake, sailing angles and sail settings...

Start off with the rudders in the locked down position. Measure down the blade 12” from the bottom of the lower casting. Mark the rudder with a line 2” long perpendicular to the 12” point (fore and aft on the blade). Using a very thin piece of line, starting at the top of the rudder pin, align the "line" with the rudder pin top to bottom (on the pins center line / axis) and check where the line intersects the mark on the rudder. Mark the point where your rudder pin axis crosses the mark you made 12" down the blade. Measure in from the front of the rudder. A larger measurement means that the rudder is raked forward more. More forward rake is less weather helm. Optimally, you should have 1 5/8” to 1 3/4” for a measurement. To achieve the 1 3/4” number, you might have to re-drill the front hole on the rudder or file away at the front of the rudder where it hits the casting. To much forward rake can cause lee helm and THAT is WORSE and even dangerous. The boats sail better and are safer if the boat rounds up slowly when the tiller is released.

Right; that's good information. What I'm looking for is say, 2-3 lbs of force necessary on the hiking stick, not 10-12 lbs. I'd prefer to not have the boat round up immediately when the tiller is released as it does currently. It's just fatiguing to be out on the lake when there's any wind at all.

I'll try it out this weekend.

BTW... the rudder-drilling template... how much rake should result from that? (in the 1 5/8 - 1 3/4 range?)